The invention is in the field of prosthetics and more particularly bioprosthetics, pertaining specifically to repair and replacement of connective tissue structures through use of heterologous animal tissue or homologous tissue.
The use of prosthetic devices within the body, such as artificial joints and plastic or metal implants of various kinds is becoming increasingly common and represents a technical field of intense activity. The use of biologically inorganic material, such as metal or plastics, in the body creates basic engineering or mechanical problems, some of which can be overcome by the use of bioprosthetic material.
There are materials which are produced by the human body or in animals which are intrinsically superior to man-made materials in their durability, toughness, slipperyness, or a certain combination of desired traits. For example, it has been found that heart valve replacement can be done using porcine heart valves. Although mechanical valves have been developed, the porcine heart valve combines the characteristics or durability, reliability, and relative silence in operation and is included in the spectrum of today's prosthetic valve replacement. Porcine pericardium has also been used both to repair injured human pericardium and, at least once, to replace a single cusp in a defective heart valve.
Until recently, because of the antigenic nature of nonautologous tissue utilization of porcine heart valves and other bioprosthetic material had not been possible due to rejection. Currently, however, heterologous and homologous tissue may be rendered stable and non-antigenic by fixation with such compounds as glutaraldehyde to permit their use as heterografts in humans.
As pointed out below, the ability to use heterogeous animal tissue possessing similar biomechanical properties as those tissues being replaced or augmented has certain advantages, such as similar modulus of elasticity and the potential for eventual biologic bonding.